Drilling Through Holes on the Mill

[rmac]

Sometimes I want to clamp a part to the mill table and drill holes through it, but not into the mill table. For non-critical projects, I usually just put a piece of MDF under the part to hold it up away from the mill table. I use MDF because it seems like it's pretty flat, stable, and uniform in thickness. But I'm wondering what real machinists do.

Same question, actually, when you want to drill some holes in a small part held in the milling vise but don't want to drill into the parallels that are supporting the part. Do you put something between the part and the parallels? Or get everything set up and then (try to) remove the parallels? Or make some wooden parallels (my favorite)? Or what?

-- Russell Mac

[Steggy]

I keep small pieces of extruded aluminum around for that sort of situation. I stick to relatively thin pieces, as they are generally more uniform in thickness than the heavier stuff.

[Rick]

Depends on the part: if its not to critical or some material that isn't very flat to start with like Cold Rolled flat bar, then plywood or whatever sacrificial material I can find.
Semi critical or heavy machine cuts will be required: I will use some pieces of alum bar stock
Very critical: 123 blocks in strategic positions and the clamps right above the 123 blocks, this depends on thickness of the part and type of operation needed. This would usually be ground plate parts.

As far as drilling small parts in the vise then I would use soft jaws, I usually make a batch of soft jaws when I make them so I have some some ready to go or just re-machine used ones.

[toddalin]

I just milled a through slot in a piece of copper strap. I first milled a piece of scrap wood to the same thickness as the width of the strap. Then I used double sided tape to secure the strap to the wood and placed the whole thing into the milling vice, (below the jaws) and milled down into the wood.

http://www.audioheritage.org/photopost/ ... 06_2_2.JPG

[Rich_Carlstedt]

Mac
In our die shop, we used MDF at times , as you do
For precise work we had sheets of Delron 3/4" thick that the work sat on , and when on the Radial drill
with big drills, then we used 2 sheets. The problem with using arcrylic sheets is they are slick so you have to make sure the part stays in location.
When using a vice, we used aluminum bar/strips almost all the time -except when drilling or milling the side of the part then used steel
so we had no cutter deflection .
We also used "tempered hardboard" which was 1/4" thick and smooth both sides and VERY consistant in thickness
They quit making it maybe 30 years ago...too bad, now they only have one side hardened !
Rich

[rmac]

Thanks, guys, for the hints. I guess I wasn't too far off except that I need to be reminded once in a while about soft jaws in the milling vise. I guess the idea there is that you make them out of aluminum and then just drill right into them as needed?

-- Russell Mac

[BadDog]

I've most often got step jaws (roughly 0.100 x 0.100) mounted on my 6" mill vise, and a similar set I made for my drill press vise. Those serve most of my purposes. For the rare larger piece of plate or weldment that I lamp to the table, as others have said, 123 blocks, or one or another parallel setup to space it off the table. If that doesn't work, MDF would be my choice as needed, though that's mostly to prevent chatter when milling through rather than drilling.

[Richard_W]

I bought a set of theses 1/32 thick parallels. They work for me.

https://www.ebay.com/itm/1-32-ultra-thi ... SwZUNfuBIL

[Mr Ron]

I would take a small block of aluminum, narrower than the piece you want to drill into and shorter than the depth of the jaws; set up in the vise on parallels; machine flat; remove parallels and set your work on top of the machined block. If you machined the block flat, then your work will be set on a flat surface. Drill your holes. Even a very hard wood would work.

[rmac]

... set your work on top of the machined block. If you machined the block flat, then your work will be set on a flat surface. Drill your holes.

What keeps the work from moving around while you're drilling the holes?

-- Russell Mac

[Harold_V]

I bought a set of theses 1/32 thick parallels. They work for me.

https://www.ebay.com/itm/1-32-ultra-thi ... SwZUNfuBIL

Thanks, Richard. I just ordered a set. Having specialized in small work, having parallels in small height increment changes is exceedingly useful.

H

[Richard_W]

I bought a set of theses 1/32 thick parallels. They work for me.

https://www.ebay.com/itm/1-32-ultra-thi ... SwZUNfuBIL

Thanks, Richard. I just ordered a set. Having specialized in small work, having parallels in small height increment changes is exceedingly useful.

H

Your welcome. I have found them very useful.

Richard W.